21223015 has 16 divisors (see below), whose sum is σ = 28536480. Its totient is φ = 15016320.

The previous prime is 21223009. The next prime is 21223051. The reversal of 21223015 is 51032212.

It is not a de Polignac number, because 21223015 - 2⁹ = 21222503 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21223015.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3180 + ... + 7249.

It is an arithmetic number, because the mean of its divisors is an integer number (1783530).

Almost surely, 2^21223015 is an apocalyptic number.

21223015 is a deficient number, since it is larger than the sum of its proper divisors (7313465).

21223015 is a wasteful number, since it uses less digits than its factorization.

21223015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10482.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21223015 is about 4606.8443646383. The cubic root of 21223015 is about 276.8656179358.

Adding to 21223015 its reverse (51032212), we get a palindrome (72255227).

The spelling of 21223015 in words is "twenty-one million, two hundred twenty-three thousand, fifteen".